You’re streaming a video. Bright yellow text flows across a dark screen: a movie title followed by a long-ish narrative. A spaceship flies across the screen, chased by a much larger one; colored laser lines streak across the screen, missiles fired by the larger craft at the fleeing spaceship. The scene then moves inside the first ship, where three robots hurry along a hallway; armed soldiers rush past them.

Finally, more than two minutes in, one of the robots speaks the first line of dialogue.

It’s the opening of Star Wars, of course. But if you couldn’t see what was on the screen, you’d be completely confused. Obviously, something needs to be done to make the movie accessible to people with low or no vision. But what?

When using a medium like video, learners need to know both what is being said and what is showing on the screen. Most people are familiar with captions and transcripts, which provide access for learners who are hearing impaired or deaf. But what about learners with impaired vision? Can visual media, including video-based eLearning, be accessible to learners with low or no vision?

Though less familiar, the solution is equally essential: audio description. “It’s not like captioning, where everybody sees it on the television in the bar or in the gym,” said Joel Snyder, president of Audio Description Associates and director of the American Council of the Blind’s Audio Description Project. “With description, you’re not aware that it’s there unless you’re using it.”

What is audio description?

Audio description fills the visual void with a narrated description of the scene, the characters, and the action, providing access to visual elements that are not described in the default audio. The description is provided between lines of dialogue and other sounds on the soundtrack; it might be detailed or quite brief, depending on the content and space available.

Audio description can be provided for live or recorded content; some theaters and concert halls offer the service, as do many museums and galleries. Some television and movie content is available with audio description—including all seven Star Wars movies. Audio description of recorded content generally omits decorative elements, such as clip art or icons that do not add new information.

The audio track with description is often a separate audio track that users can select in the same way as an alternate language track or via an accessibility menu. Viewers who activate the audio description option on a video player or streaming service will hear the augmented track; other viewers will hear the default audio, sans description.


Description is not the only option

For some types of content, another approach is possible: designing content, particularly eLearning, to be accessible from the ground up.

“Universal design is all about one-size-fits-all; basically, none of this separate-but-equal,” Snyder said. For example, an audio tour at a museum can be accessible using either approach.

“A regular audio tour, if you will, provides a lot of information—background, facts, and such,” Snyder said. “That same tour can be written so that it provides descriptive material.” When done well, the added description will not seem “odd” to sighted museumgoers, Snyder said, but the tour is more accessible—to all hearing museum visitors. “Some museums end up having two separate tours, which seems a little silly to me. It’s unnecessary, especially when people talk about universal design,” he said.

eLearning and audio description

Likewise, some types of eLearning, such as short slide-based presentations, offer two paths to accessibility.

  • The presenter speaks aloud all the text that appears on the screen, along with detailed explanations; she also describes aloud all charts, graphs, or photos. The resulting short video is accessible, as-is, to learners who have visual impairments. All the relevant information is in the default audio.
  • The presenter, as is all too common, does not describe the images or even read all the text that appears on screen. This video would need audio description to be accessible to learners with visual impairments.

“I encourage people to do self-description, which is not ‘I’m six-foot-five and I have black hair.’ Self-description is providing the description yourself, during your presentation,” Snyder said. “Similarly, if you’re going to present a video, it should be audio described, and it should be captioned.”

Other types of eLearning content present a greater challenge. For instance, consider an interactive activity that presents interactions among several characters. The learners’ task is to resolve communication problems. In one scenario, a character strides out of the room. Another puts on a headset and deliberately—and silently—turns away from the group. Here, the characters’ actions, facial expressions, and body language are all relevant to learners’ understanding of the group dynamics. Without an audio description, learners with visual impairments would miss critical elements of the content.

What about a five-minute training video that walks learners through the steps of a process? Ideally, the default audio would include an audible explanation of each step, rather than assuming that all learners will understand what they are watching the actor do. If thorough explanation is part of the default audio, audio description is not needed.

Description aids understanding

Federal law requires that some web content and eLearning be accessible, including captioning, descriptive “alt” tags on images—and audio description. (See “Section 508 Refresh: The Clock Is Ticking on eLearning Accessibility Requirements” for information on these requirements.)

But beyond legal requirements, description of the visuals in eLearning content is simply good design. “Any image that you project, any image that’s up there, whether there’s an alt tag or not, should be described in text somewhere,” Snyder said. “Going back to the question of universality—people seem to learn in different ways; that makes it more accessible to anyone. They hear as well as see the particular image. That’s a lot of what eLearning involves, I think.”

Research indicates that the majority of people who use captions are not deaf or hard of hearing. They use captions to help them focus, for example, or to better understand the material. (See “Improve Engagement, Focus, and Comprehension with Closed Captions for eLearning Videos.”)

Snyder says that’s true of audio description as well. “Sighted people find that they notice things that are pointed out to them. You might go to a film, you like it, and you go to see it again. And, ‘Oh, whoa, I didn’t see that the first time.’ Well, you probably would have seen it the first time, had the audio description been on.”

Description might also aid learners in ways that go beyond the specific content: “There’s increasing evidence that description aids literacy, in the same way that captioning helps kids or speakers of other languages to learn English. Hearing varied word choice, hearing synonyms, hearing similes and metaphors helps you develop a sense of literacy. In that way, it’s helpful for everybody,” Snyder said.

Blind Spot blogger Hannah Thompson’s eloquent post, “Audio Description,” makes it clear that all video-watchers could benefit from the additional narration: “Last night I watched a film for the first time in my life. I have been to the cinema hundreds of times and watched thousands of videos and DVDs, but yesterday I realized what watching a film really means. … Hearing a little bit of extra detail as I was watching the film was a hugely enriching experience. It was unobtrusive, informative, and engaging. And it made me realize that there are … elements of film that I have been missing.”

A three-step process

The three steps in creating audio description use different skill sets and are not necessarily performed by a single developer.

1. Writing a script
The script is a description of the scene, the characters, the action—everything except the dialogue and other sounds. The describer should include details that enhance understanding: mentioning what a character is wearing or eating; describing the flash of anger that crosses an actor’s face or the care he’s taking to hang a photo just so. Description of items for a site tour or art gallery tour should mention what a sculpture is made of, the colors that dominate in a painting, the mood a photo creates. Other salient details could include placement of items relative to the listener or to walls, doors, or other objects; items’ size; and description of the lighting and environment. The describer has to strike a balance between providing relevant information and overwhelming the listener.

2. Voicing the description
This requires recording each line of the script, with pauses between lines. Depending on the project, professional voice talent might be used—or an audio describer can both write and voice the script.

3. Editing the audio
Any video editing tool that allows the editor to add and edit audio tracks, or a multiplexing/demultiplexing tool, such as Subler for Mac, can be used to integrate the audio description with the default audio.
The soundtrack takes precedence over the audio description, which is integrated into pauses in the default audio. “Hopefully, the description fades into the background; it doesn’t dominate the experience,” Snyder said. Description does not have to sync perfectly with the action in the video, but the description must be close enough that it remains relevant.

Adding audio description is “really not complicated at all if you’re talking about just slides or images. It depends on the eLearning course, what the structure is,” Snyder said, and many developers do it themselves. For content that is heavy on videos, “You generally want to have a professional look at the video, listen to the video, and create description that fits within the pauses between bits and pieces of dialogue or critical sound elements.”

For companies that produce large amounts of eLearning content, Snyder suggests a training session for developers. “There are fundamentals to it; it’s not just labeling. There’s a way to do description that represents best practices,” he said.

Audio Description Associates and other audio description companies offer training that ranges from a few hours to several days. Snyder’s book, The Visual Made Verbal: A Comprehensive Training Manual and Guide to the History and Applications of Audio Description, also provides guidance.


Snyder, Joel. The Visual Made Verbal: A Comprehensive Training Manual and Guide to the History and Applications of Audio Description. Indianapolis, IN: Dog Ear Publishing, 2014.